Highly diastereoselective synthesis of 3-methylenetetrahydropyrans by palladium-catalyzed oxa-[4 + 2] cycloaddition of 2-alkenylbenzothiazoles
作者:Xiaoxiao Song、Lei Xu、Qijian Ni
DOI:10.1039/d0ob01434f
日期:——
A highlydiastereoselectivesynthesis of 3-methylenetetrahydropyrans via palladium-catalyzed oxa-[4 + 2] cycloaddition of 2-alkenylbenzothiazoles with allyl carbonates bearing a nucleophilic alcohol side chain is presented. This synthetic methodology tolerates a wide variety of 2-alkenylbenzothiazoles and afforded the desired 3-methylenetetrahydropyrans in good yields and excellent dr. In addition
Highly diastereoselective synthesis of benzothiazolo[3,2-<i>a</i>]pyridines <i>via</i> [4 + 2] annulation reaction of 2-vinylbenzothiazoles and azlactones
benzothiazolo[3,2-a]pyridinederivatives was readily obtained in good to excellent yields (68–96%), with high diastereoselectivities and tolerating quite a broad scope of substituents. By using chiral phosphoric acid catalyst, the desired products were obtained in high enantioselectivities, up to −94%. This methodology provides a rapid and useful method for constructing fused benzothiazole derivatives.